(1) Field of the Invention:
The present invention relates to a catalyst for direct liquefaction of coal and a method of directly liquefying coal by using such a catalyst. More specifically, the invention is to provide a catalyst for direct liquefaction of coal which has a high catalytic activity and is cheap, and to provide an industrially advantageous method of directly liquefying coal by using such a catalyst.
(2) Description of the Prior Art:
The technique of directly liquefying coal is to convert solid coal into liquid hydrocarbons, and includes thermal cracking, hydrogenation, hydrogenolysis and the like from the standpoint of the chemical reaction. Among them, the hydrogenation and the hydrogenolysis are slow in the reaction rate, so that it is necessary to use a catalyst for accelerating the reaction. As the catalyst, there are (A) metal chlorides, (B) metal oxides and the like. The metal chloride catalyst (A) (e.g. zinc chloride, antimony chloride, tin chloride and the like) is a powerful catalyst but is corrosive and therefore has not been industrially successful. As the metal oxide catalyst (B), there have been well known oxides of iron, nickel, cobalt, molybdenum, tungsten and the like. Among them, nickel, molybdenum, and tungsten are expensive and/or have problems with sulfur resistance. Accordingly, cheap and disposable iron oxide catalysts are promising and have been used with sulfur as a promotor in recently developed coal liquefaction processes. However, the iron oxide-sulfur (or iron sulfide)-combined catalyst is lower in the catalytic activity than molybdenum or tungsten oxide catalyst. Consequently the volume of the reactor must be larger and the construction cost of the system becomes more expensive. Under these circumstances, a need exists for an effective, inexpensive catalyst that is sulfur resistant.